Plug-type connections are known in the prior art, whose socket is closed by a lid if the plug is not plugged in, the lid being rotatably mounted on the socket housing. In most cases, the lid is preloaded by means of a spring, so as to close the plug-in opening of the socket automatically as soon as the plug is pulled out of the socket. Most of the plug-type connections of this kind known in the prior art have a snap-in nose formed on the lid of the socket which, if the plug is plugged in, is engaged with or engaged behind the plug itself or a suitable protrusion formed on the plug, so that the plug is secured against slipping out of the socket. The spring preload of the lid makes sure that the snap-in nose of the socket lid remains constantly engaged with the plug. Thus, the plug is always secured against slipping out of the socket. A plug-type connection of this kind is known, for example, from EP 0568030 A1. In this plug-type connection sharp-edged structures are formed on the snap-in nose of the socket lid, which interact with sharp-edged structures on the plug side. By this, it is to be prevented at any rate that the hinged lid of the socket opens, thereby releasing the plug inadvertently, with the consequence that the plug can slip out of the socket.
The problem of plug-type connections of this kind is that a strong tensile load acting on the plug or the cable connected to the plug may cause damage to the plug-type connection or the cable. The plug-type connection can be used, for example, for the electrical interconnection between a towing vehicle and a trailer or implement. The plug-type connection is not configured, however, to couple a towing vehicle and a trailer to each other mechanically. To this end, a mechanical coupling is provided. It occasionally happens that the mechanical coupling between the towing vehicle and the trailer is undone without simultaneously disengaging the electrical plug-type connection. This negligence may result in the movement of the towing vehicle without the trailer which, as a rule, causes damage to the plug-type connection and results in the tearing off of the electrical connecting cable.
To overcome this problem it has already been proposed in DE 1207983 A to attach a flexible clamp to the socket lid, which runs across the cable hanging down from the plug. Pulling on the cable makes the cable get tensioned, thereby starting to displace the clamp out of its rest position. If a certain tensile load is reached the displacement of the clamp opens the socket lid. The snap-in nose formed on the socket lid thereby releases the plug, allowing it to be pulled out of the socket.
A problem occurs if the tensile load acting on the plug and the cable does not act in the longitudinal direction of the plug. This is the case, for example, if the towing vehicle is not driven straight forward, but at a certain angle relative to the longitudinal axis of the trailer. In this case the cable is not tensioned in the longitudinal direction of the plug, but obliquely to the longitudinal direction of the plug. In the plug-type connection known from DE 1207983 A this problem is overcome by providing the flexible clamp attached to the socket lid with a certain width, allowing it to be displaced also by an obliquely tensioned cable. With respect to cables tensioned obliquely relative to the longitudinal direction of the plug this solution is suitable only to a limited extent, however. Furthermore, the resultant cable run has proved to be disadvantageous. Especially if the pull-out angles are very oblique, the cable is very strongly loaded at the point of entry into the plug at the rear end of the plug. If the pull-out angles are very oblique, a strong kink in the cable is caused at this point.